The chief of the Fukushima No. 1 nuclear plant said in testimony before his death that he feared the core meltdowns he was trying to contain in March 2011 would cause catastrophic damage to eastern Japan, government documents show.

“Our image was a catastrophe for eastern Japan,” Masao Yoshida told a government panel probing the Fukushima nuclear crisis. “I thought we were really dead.”

Yoshida wanted his testimony to remain confidential after his death because the account might contain mistakes from the confusion created by the crisis triggered by the massive earthquake and tsunami of March 11. But leaks to two major Japanese dailies prompted the government last week to announce its intent to disclose most of the documents, which detail the drama that took place during the worst nuclear disaster since Chernobyl.

According to documents obtained Saturday, Yoshida rejected the government’s opinion that the plant owner Tokyo Electric Power Co. attempted a “complete withdrawal” of all staff from the plant on March 15. He was also angry with Tepco headquarters and the administration of then-Prime Minister Naoto Kan, which he thought had failed to understand the dire situation his workers were facing on the ground.

“We did not escape,” Yoshida is quoted as saying in the roughly 400 pages of testimony, scheduled to be released next month.

Yoshida’s testimony was reflected in the panel’s final report in July 2012 along with those of more than 770 other people involved in the disaster. Yoshida died of esophageal cancer the following July at age 58.In May, the daily Asahi Shimbun reported in Japanese and English that 90 percent of the plant’s workers left the damaged complex despite being told by Yoshida to stay put, citing his testimony. But Yoshida did not say they were violating his order on purpose.

At one serious point in the crisis, on March 14, 2011, when it looked like the containment vessel of reactor No. 2 was going to fail and pollute the area with high amounts of radiation, Yoshida said he thought he was finished.

“I really don’t want to recall this part,” he said, because he was bracing for the worst — a total failure in which the fuel melts and breaches both the pressure vessel and the containment vessel.

“All the radioactive materials would go out and be scattered,” he said.

But the workers who were failing to inject water into the No. 2 reactor to cool the molten fuel caught a break when the air pressure in the containment vessel dropped, allowing the fire engines to get the water in.

When the Asahi first reported the contents of the testimony, the government said the documents would be kept confidential to honor Yoshida’s wishes. But the government has since reversed itself because withholding the documents amid the leaks might actually contradict Yoshida’s wishes.